1. Field of the Invention
The present invention relates to a mobile terminal device. In particular, it relates to a mobile terminal device that has a display element protected against a great impact occurring when the device is accidentally dropped, for example.
2. Description of the Related Art
Mobile terminal devices used for telephone conversation or transmission of various kinds of information, such as mobile phones, personal handy-phone systems (PHSs) and personal digital assistants (PDAs), have been developed and widely used.
Such mobile terminal devices have a display unit, such as a liquid crystal display (LCD), serving as a man/machine interface for displaying information being transmitted. To address the increasing amount of information transmitted, the display screen of the display unit is becoming larger and larger, enabling effective display of vast amounts of textual or graphical information (including photographs) acquired from a network, such as the Internet, or a host computer.
As a conventional technique, there has been disclosed an electronic device with a liquid crystal display whose frame, into which the display window of the liquid crystal display unit is fitted, and is designed having various thicknesses to reduce breakage of the display unit even if the housing is bent by an external impact or pressing force (for example, see Japanese Patent laid-open Publication No. 122037/2000, p.3, FIGS. 1 and 2). Besides, there have been disclosed a portable information terminal device, a support structure for a flat panel display and an electronic device that have an internal shock absorbing mechanism to prevent breakage of the device subjected to a shock (for example, see Japanese Patent laid-open Publication No. 175608/2001, p.2-3, FIGS. 1 and 2, and Japanese Patent laid-open Publication No. 278467/2002, p.4, FIG. 1). In addition, there have been disclosed a holder structure for a liquid crystal display element that improves the protection level of the liquid crystal display element mounted on an electronic device, such as a mobile phone, and the electronic device having the holder structure (for example, see Japanese Patent laid-open Publication No. 272660/2001, p.3-4, FIG. 1). Furthermore, there is disclosed a folding mobile phone that can be folded not to expose the metallic part to the outside (for example, see Japanese Patent laid-open Publication No. 51132/2002, p.3, FIG. 1).
As disclosed in the publications described above, some mobile terminal devices, such as mobile phones, are of a folding type. For example, conventional mobile phone 20 shown in FIG. 1 has receiving section 21 and transmitting section 22 connected to each other by hinge section H. Receiving section 21 has display section 23, such as a liquid crystal display panel, and transmitting section 22 has a plurality of key switches 24.
For example, as shown in the cross-sectional view of FIG. 2, receiving section 21 of mobile phone 20 typically comprises front case 25, display element 26, holder 27, substrate 28 and back case 29. Holder 27 is attached to substrate 28 and holds display element 26, such as a liquid crystal display panel, on the front side of mobile phone 20 (that is, on the opposite side of substrate 28). Front case 25 serves to protect display element 26, and at least a part thereof corresponding to the display area of display element 26 is made of a transparent material to allow a user to see the characters or graphics on the display area.
In the case of mobile phone 20 configured as described above, for example, if the user accidentally drops it onto ground G or the like during telephone conversation, the impact causes display element 26 to bend as shown in FIG. 2. If the deformation by the bending exceeds a certain limit, display element 26 may break.
To avoid such breakage of display element 26, the Japanese Patent laid-open Publication No. 272660/2001 described above discloses an arrangement shown in FIG. 3. Specifically, holder 27 for fixedly holding display element 26 has a plurality of (two, for example) pins 30A and 30B on the back side thereof, and pins 30A and 30B are fitted into holes 31A and 31B formed in substrate 28. Holder 27, which has a substantially rectangular shape, has side walls 32A and 32B that extend along the periphery of display element 26 when holder 27 holds display element 26. Pins 30A and 30B described above are disposed at corners where side faces 33A to 33C of side walls 32A and 32B intersect with the bottom of holder 27 on which display element 26 is mounted. Display element 26 on the holder 27 is connected to a driving section (driver) on substrate 28 via flexible substrates 26A and 26B or the like.
However, the conventional technique described above has some problems. First, it is difficult to increase the display area. This is because the display element is inadequately protected. According to the conventional protective measure, the display element is protected by pins provided at the highly rigid peripheral part of the holder. However, if the display element is subjected to a great impact when the folding portable terminal is dropped, for example, the portable terminal is deformed as shown in FIG. 2. The conventional technique, which takes no protective measure at the middle part of the holder, does not provide against increased bending of the display element due to increase of the display area, and thus, the display element may break.
Second, it is difficult to reduce the thickness of the mobile terminal device. This is because the display element is inadequately protected. As with the case described above, according to the conventional technique, which takes no protective measure at the middle part of the holder, as the rigidity of the whole device decreases as the thickness of the device is reduced, it needs to increase the thickness of the holder to prevent an increase of bending of the display element.